Apparatus for varying the pitch of aeroplane propeller blades



Feb. 6, l934.- .y Q 1 CHANCE Er AL l 1,946,387

APPARATUS FOR VARYING THE FITCH OF AEROPLANE PROPELLER BLADES original Filed Marcnls, 1930 s sheets-sheet 1 ATTRN EY.;

Feb. 6, 1934. C; T, CHANCE ET AL 1,946,387

APPARATUS FOR VARYING THE FITCH OF AEROPLANE PROPELLER BLADES Original' Filed March 19, 1930 3 Sheets-Sheet 2 ATTORNEYS' Q, "gi @ANCE Er AL 1,946,387

APPARATUS Fori VRYING THE FITCH 0F AEROPLANE PROPELLER BLADES Original Filed March 19, 1930 3 Sheets-Sheet 3 ATTQRN EYS patented ab. 6, 1934 '1,946,381

APPARATUS FOR VARYING THE PITCH OFV AEROPLANE PROPELLER BLADES Charles T, lChance and Murray K. Patten, Detroit,

Mich., as sgnors, by mesne assignments, 4,tov Walter F. Stimpson, Detroit, Mich.

f Application March 19, 1930, serial No 437,260 Renewed July 28, 1932 This invention relates ,to propellers such as are attached to a standard propeller without changdriven by engines on airplanes, dirigibles, some ing either the propeller or motor. forms of motor boats, etc., and has for one of Another object of our invention is to produce its objects theproducion of relatively light but such a mechanism which will'absorb no power practical and efficient means whereby the blades from the engine save when the pitch angle of 'so may be readily and positively turned about their the blade is actually being changed, except for axes to any desired pitch while the propeller is the power absorbed bythe actual weight of the rotating. y device, which weightis much less than that of any Another object of 'our invention is to render kindred device now in use. l l0 such pitch variation constantly controllable from Other objects and yadvantages will be apparent 65 the pilots seat, v from the following description -wherein reference Another object of our invention is to furnishV is made to the accompanying draWingS Showing to the pilot convenient means of ascertaining a preferred embodiment of our invention, and and regulating the blade angle or geometrical whereinV similar vreference numerals designate pitch of the propeller while it is in rotation. Similar parts throughout the several views. 70

A further object of our invention is to achieve In the drawings: such desired results without variation of standard Figure 1 ShoWS a propeller embodying our npropeller construction, vention mounted on a typical tractor monoplane, A further object of our invention isto so cen vand the relative positioning of the control and Wi ralize the positioning of the pitch-varying mechindicator devices. p 75 anism within the area swept by the boss portion Figure 2 is an enlarged Side elevation. partly of the propeller that such mechanism will create in Section, of 0111 invention aXed to the hub and very little if any propeller interference affecting lboss of a propeller ofiandard Split-hub Conthe thrust thereof by changing the air flow in Str'lloiionl f the slip srearn. Figure 3 is a cross section taken substantially The advantages which would accrue fromthe 0n the line 3--3 of Figure 2, and looking in the development of a practical 'controllable pitch direction of iSl'le arrows, also Showing the oonpropeller as contrasted with a propeller having `eirlletion of the Pitch angle indicator. fixed blades or blades adjustable only when at Figure 4 iS a Similar Sectional View taken subrest,` have long been recognized, for such pitch Stantially 0n the line 4 4 0f Figure 2, and look- 85 variation eiTects useful changes n ot only of the `ing inthe direction of the arrows. lthrust of the propeller, but also the motor speed *Figure 5'iS alongitudinal Section of-a standat any given throttle point to accomplish a deord 'DWO blade Split hub, With portions of the sired thrust or speed. Thus it becomes possible blades Clamped therein.

e for an airplane to take off' from a much smaller Figure 6 iS e Section teken substantially on the 90,

landing seid than usual, with its blades set at a line 6-6 0f Figure 2, looking in the direction of low pitch angle, and a consequent higher motor the an`0W5 speed, but thus sacrificing air speed for a quick Flg'ul'e 7 is a- VW Partly mectlon, taken Subtakeff, and aftep the plane is in the an., to stantially on'the line 7-7 of Figure 2, and looking 49 increase the pitch angle and consequently reim the dlretlon of @he arrws'. 95

duce the speed of the engine and increase the Flgure 1s a Sectlomfl View smularto Flgure 3 speed of the plane, asdesired. It is also possible but Showmg the posmolimg of th? parts after to conserve fuel by slowing down the motor at the-ca'm has maden parilal revolutmn fun throttle Figure 9 is a fragmentary elevation, partly in section, showing my pitch angleindicator and Wide adaptabihty of the propeller to varying the positionmg thereof 10p load, plane and air conditions, greater air speedv Figure 1o is a plan vew of the clamping memand economy, and better climbing and ground' ber used to supportthe cam and pinion performance, are among the other highly ad- Referring now to thendrawmgs;

50 vantageous results produced by our inventiom- Reference numerals 11 and 11a, (Figure 2) im r which may be summed up in the Conclusion that dicate the twohalves of a standard split hub for 105 the flexibility of performance of an'airplane is airplane propellers of adjustable pitch. In place here y greatly enhanced. y of the usual clamping member which ordinarily Another object of our invention is to' produce encircles each extremity of such a hub, however,

such a pitch varying mechanism which may be we use a two-part clamping member 'of the `form no designated by the numerals 12, Figure 2, and which is shown in detail in Figure 10, the front ends of which may be drawn toward each other for tightening in the usual fashion, as by the bolts 13, and cooperating castle nuts and cotter pins, 31 and 32. Projecting from the rear ends of each half of the clamp 12 are the supports 14 and 15 for the shouldered bolt 16 which constitutes a shaft upon which freely revolve the cam 17 and pinion 18. The cam 17 and pinion 18 are keyed or splined together, as by being splined to they revolving sleeve 50, so that they both revolve as a unit about the shaft bolt 16. The shoulder 19 on the bolt 16 (Figure 6) serves to prevent undue compression of the ends 14 and 15 of the clamp 12, which might bind the cam and pinion 17 and 18 against rotation. The cam here shown is of the cylindrical and uniform motion return type, within the track of which slides? the pin 21 (Figure 7) which is aixed to the extending lever arm portion 22 of the one-piece clamp 23. One of the clamps 23 is tightly secured on the boss portion of each propeller blade adjacent the end of the hub. In order to allow passage of the clamp 23 over the shoulders 24 and 25 (Figure 5) von the blade ends, the clamp 23 is made materially but uniformly larger in interior diameter than that portion of the blade bossit is intended to encircle, and a split ring 26 (Figures 3, 4 and 8), is introduced between clamp and blade. The split ring is suitably fastened rmlv in place, as by the dowels 27.' The clamp ring 23 is tightened on the split ring and the propeller by means of the bolt 28, and locked in tightened position by the castle nut 29 and cotter pin 30. In their relation to the interior of the hub the blade ends or stubs are held in what might best be described as a tight slip fit. The fit is metal to metal, and tight enough so that a very considerable force is required to turn the blades relatively to the hub. This force We produce by means of the worm, 33, which simultaneously turns the pinions 18 and cams 17, thereby reciprocating the pin 21 and partially rotating the blades. The worm 33, which is of very gradual pitch, is formed on the outer peripheryof the ring member 34, which also has formed thereon a surface acting as a brake drum, 35. The ring member 34 is mounted in slip-fit relation on theanged cylindrical member 36, and is rotatable relatively thereto, but normally turns with the member 36. The fianged cylindrical member 36 is flxed to a portion of the hub, as 11 and rotates with the propeller and propeller shaft when the latter is driven by the motor. The braking surface 37 may be increased by being formed in V shape as herein shown. Cooperating therewith and surrounding the drum is the brake shoe 38, which is faced with a suitable brake lining, as 39. The brake shoe is fixed against rotation, one end being pivoted on the pin 40 (Figures 6 and 7). The brake shoe 38 is normally held clear of the drum 35 by the leaf springs 41, Figures 2, 6 and 7. The pin 40 and the spring arms 41 are secured to a fixed portion of the fuselage or motor, or motor mounting. vAs here shown they are attached to the front of the crank case. The free end of the brake band or shoe 38 has aprojection or terminal fitting, herein shown as the flange 42, with which cooperates the cam lever 43 (Figures 6 and 7) arranged to force the brake band against the drum by decreasingits diameter by exerting a longitudinal pull on the free end of the band 36, upon a partial rotation thereof. Integral with the cabin or cockpit adjacent the pilots seat.`

The ring member 34 carrying worm and brake drum is held against axial movement along the surface of the member 36 by the flange 48 and the rollers 49 (Figures 2 and 10), between which it is firmly but rotatably held. The rollers 49 are mounted in the clamp ring 12, as upon shafts 52 (Figure 10) In operation, all parts except the brake band 38,

2 and the mechanism for applying the brake, rotate freely with Athe propeller, including the ring member 34 which carries the worm 33. When the brake is applied, however, the drum 34 is stopped or; slowed up, depending upon the pressure exerted. The rest of the parts continue to revolve with the propeller, and accordingly the pinions 18 revolving about while in mesh with the Worm 33 are caused to rotate on their shafts at relatively low and synchronized speeds. Thereby the cams 17 are turned and the pins 21 are simultaneously reciprocated or moved laterally by the track of the cam. As herein shown, for each revolution of the cams 17 the blades are moved through fixed arcs and returned to their original positions, though obviously any desired cam arrangement may be made= The adjustability of the clamp rings and of the cams 17 enables the blades to be set to move in absolute synchronism, and they will permanently remain so because the parts at each end ofthe hub are 4identical and are driven by the same worm.- The correlated cam and pinion units (17 and 18) are moreover readily interchangeable by mere removal of the bolts 16. Thus, assuming that the cams shown move the blades through an arc of 10 degrees and return them through the same arc,.cams may be substituted which rock the blades through only a 5 arc, or which impart any other desired motion or degree of motion. The minimum and maximum pitch angle is governed by the adjustment of the clamps 23 on the blade bosses, which must of course be adjusted as nearly parallel as possible. Assuminggfor example that the minimum pitch angle is adjusted to 35 degrees, cams imparting a 10 rotation of each blade, will, while the brake is on, slowly rock the blades through the angle from 35 to 45 degrees. If without other adjustment 5 movement cams be substituted for those imparting a movement of 10, the blades will then be rocked from 35 to 40 degrees.

The blades are locked against turning on their axes, except when the brake is applied, by the form and positioning of the parts. The pin 2l fits snugly in the cam track 20, which is of relatively gradual pitch. Any tendency of the blades to turn is accordingly opposed by the lateral pressure of the pin 21 against the side of the track 20, and further guarded against by the meshing' of the teeth of the pinion 18 (to which the cam is attached) with the very gradually pitched teeth of the' worm 33, which prevent rotation of the pinion 18, and consequently of the cam 17 on their common axis, save when the worm moves relatively to the pinion. The same engagement of the pinions 18 and worm 33 serves'to increase the friction between the ring member 34 and the parts flxedly annexed to the propeller and propeller shaft, thereby preventing any movement of the ring 34 relative to the other revolving parts except when the brake is applied.

In order to enable the pilot to ascertain at any time the pitch angle of the blades, we provide indicating means coacting with a projection, such as thejoracket 53, aixed to each of the clamping members 23, and carrying rollers 54. The axis of the roller wheels 5,4 is preferably on a radial line projected from the axis of the propeller shaft. Movably mounted in such manner that it may be readily moved into the orbit of the rollers 54, is the mushroom head (Figure 9) carried on the sleeve 56 which is herein shown as slidably mounted on and spri g-connected with the rod 57. Within the sleeve 56 is the helical spring 58, afxed at one end to the mushroom head, and at the other to the end ofthe rod 57. The spring 58 is both a tension and a compression spring. 'Ihe rod 57 is slidably supported in the friction block 68, which fits the rod tightly enough to prevent movement of the rod 57 by compression of the spring 58. Attached to the sleeve 56, or integral therewith, as at 78, is a perforated ear to which the wire 59 is attached. The rod 57 is in direct mechanical connection with a lever convenient to the pilot. (See Figure l.) The wire 59 is also in direct mechanical connection with an indicator in view of the pilot, which may be in the form of a needle 60, (Figure 3) normally held in one position on its dial 62 by the spring 61. When the mushroom head is projected forward far enough to be struck by the revolving rollers, a vibratory or reciprocating movement, depending vron the speed of the motor, is imparted to the needle by means of the wire 59. Withdrawing the head until the vibration of the needle practically ceases will allow ascertainment of the position of the needle 60 on the dial 62, which is calibrated to reveal the degrees of pitch of the blades at various points, or in other suitable manner.

While it will be apparent that the illustrated embodiment of our invention herein disclosed is well calculated to adequately fulll the objects and advantages primarily stated, it is to be understood that the invention is susceptible to variation, modification and change within the spirit and scope of the subjoined claims.

What we claimis: l

l. Means for varying the pitch of a propeller blade while in rotation, comprising a friction driven worm gear coaxial and normally revolving with such propeller, means anchored on a fixed member for imposing a direct braking action on the worm to limit its rotation relatively to the propeller, and means for utilizing such difference of rotative speed for the turning of said blade on its longitudinal axis.

2.- Means for varying the pitch angle of a propeller blade which is rotatable on its longitudinal axis, while the propeller is in rotation, comprising a friction driven worm gear concentric with the axis of rotation of and normally revolving with said propeller, a brake pivoted on a fixed member and operatively connected with said worm for limiting the rotative speed thereof relatively to the propeller, a planetary pinion supported by the hub portion of said propeller on an axis transverse to the longitudinal axis of the propeller, and rotatable about said transverse axis, the teeth of said pinion being at all times in engagement with the teeth of said worm gear, whereby limitation of the rotative speed of said worm gear relatively to the speed of revolution of said propeller and pinion about the propeller shaft imparts 'a rotative movement about its own axis to said pinion, and means including a cam and lever for applying the rotation of said pinion to the turning of said propeller blade on its longitudinal axis. f

3. Means for varying, while revolving about the propeller shaft, the pitch angle of a propeller blade Whichis rotatable about its longitudinal axis within lthe hub of said propeller, comprising a friction-driven worm gear concentric with the axis of rotation of and normally revolving with said propeller, a brake pivoted on'a fixed member and operatively connected with said worm for selectively limiting the rotative speed thereof relative to the propeller, a pinion supported by the hub portion of said propeller and rotatable on its own axis, the teeth of said pinion being at all times in engagement withthe teeth of said worm gear, whereby limitation of the rotative speed of said worm gear relatively to the speed of revolution of said propeller and pinion about the pro.- peller shaft imparts a rotative movement on its ownaxis to said pinion, a cam driven by said pinion, a clamp affixed to said propeller blade, and a follower aixed to said clamp adapted to operatively engage said cam, whereby a rotative movement is imparted to said propeller blade by the application of said brake.

4. Means for varying the pitch of a propeller blade while in rotation, comprising a frictiondriven worm gear normally revolving with such propeller, means anchored on a fixed member for limiting the rotation of said worm relatively to the propeller, and means for utilizing such difference of rotative speed for the turning of said blade on its longitudinal axis, a lateral projection carried by said blade, a member fixed relatively to the propeller, yieldably supported and adapted to be contacted by said projection at each revolution of the blade, means for withdrawing said xed member from such intermittent contact by said projection, and means for ascertaining the position of said fixed member at the point where such contact ceases, wherefrom may be derived the pitch angle of said blade.

5. In combination with a propeller formed with a hub and a plurality of spaced blades `frlc tionally clamped in said hub at their inner ends, a worm gear frictionally mounted upon and normally rotating with the central portion of the hub, a plurality of worm pinions meshing with said worm gear and respectively carried by the blade-engaging rportions vof the hub, a cam mounted to rotate with each of said pinions, means carried by the blades and coacting with said cams for partially rotating the blades on their longitudinal axes whenever the cams are rotated, and means anchored adjacent the propeller hub for causing the worm gear to rotate at a different speed than that of the propeller hub whenever desired. f

6. In combination with a propeller formed with a hub and a plurality of spaced blades frictionally clamped in said hub attheir inner ends, a worm gear frictionally mounted upon and normally rotating with the central portion of the hub, a plurality of worm pinions meshing with said worm gear and respectively carried by the blade-engaging portions of the hub, a cam having a continuous peripheral groove therein mounted to rotate with each of said pinions, an arm projecting from each blade and carrying a pin engaging in the adjacent cam groove, and means for causing the worm gear to rotate at a different speed from that of the propeller hub. f

7. In combination with a propeller formed with a hub and a plurality of spaced blades frictionally clamped in said hub at their inner ends, a worm gear frictionally mounted upon and normally rotating with the central portion of the hub, a plurality of Worm pinions meshing with said worm gear and respectively carried by the blade engaging portions of the hub, a cam mounted to rotate with each of said pinions, means carried by' the blades and coacting with said cams for partially rotating the blades on their longitudinal axes whenever the cams are rotated, and a brake carried by a xed member adjacent the propeller hub and movable into engagement with the worm gear whenever desired to thereby cause the worm gear to rotate at a lesser speed than that of the propeller hub. v

8. In combination with a propeller formed with a hub and a plurality of spaced blades frictionally clamped in said hub at their inner ends, a worm gear frictionally mounted upon and normally rotating with the central portion of the hub, a plurality of worm pinions meshing with said worm gear and respectively carried by the bladeengaging portions of the hub, a cam having a continuous peripheral groove therein mounted to rotate With each of said pinions, an arm projecting from each blade and carrying a pin engaging in theadjacent cam groove, and means for caus- I ing the worm gear to rotate at a different speed from that of the propeller hub, said pin-carrying .arms being carried upon clamps adjustably encircling the blades.

9. In combination with a propeller formed with a hub and a plurality of spaced blades frictionally clamped in said hub at their inner ends, a Worm gear frictionally mounted upon and normally rotating with the central portion of the hub, a plujwith each of said pinions,'an arm projecting from each blade and carrying a pin engaging in the adjacent cam groove, and means for causing the worm gear to rotate at a different speed from that of the propeller hub, said cams being removably connected with their respective pinions, and said pin-carrying arms beingadjustably mounted upon the respective blades 10. In combination with a propeller formed -with a hub and a plurality of spaced blades frictionally clamped in said hub at their inner ends, a worm gear frictionally mounted upon and normally rotating with the central portion of the hub, a plurality of w( '.m pinions meshing with said worm gear and respectively carried by the blade-engaging portions of the hub, a cam mounted to rotate with each of said pinions, means carried by the blades and coacting with said cams for partialy rotating the blades on their longitudinal axes Whenever the cams are rotated, said worm gear also carrying a brake drum, and a brake anchored adjacent the propeller hub and movable into engagement with the brake drum of the worm gear whenever desired to thereby cause the Worm gear to rotate at a lesser speed than that of the propeller hub.

j 11. In combination with a propeller formed with a hub and a plurality of spaced blades frictionally clamped in said hub at their inner ends, means carried by the hub and blades for varying the pitch of the blades, a projection carried by a blade to swing with the blade when its pitch is changed, means for indicating'the pitch of the blades comprising a bracket adjacent the propeller and fixed relatively thereto, a slidable rod frictionally engaging within the bracket, a head reciprocable on said rod, and movable into the orbit 'of said projection, a combined compression and tension spring secured to both the rod and head, a dial, a pointer cooperating therewith and spring-pressed toward one extremity thereof, and a flexible connection between the head and pointer for indicating on the dial the position of the head when moved into the orbit of said projection.

12. In a controllable pitch propeller, a hub, means for driving the hub, a plurality of blades held in the hub and pivotal about their longitudinal axes therein, and means for turning the blades in the hub, including a lever attached to each blade outside the hub, a rotatable worm, and means for applying differences of rotational speed between the hub and the worm to move the lever and so turn the blades in the hub.

13. In a controllable pitch propeller, a hub, means for driving the hub, a plurality of blades held in the hub and pivotal about their longitudinal axes therein, and means for turning the blades in the hub, including a lever attached to each blade outside the hub, a rotatable worm coaxial with the hub, means for driving the worm, and means for applying differences of rotational speed between the worm and therhub to move the lever and so turn the blades in the hub.

14. In a controllable pitch propeller, a hub,l

means for driving the hub, a blade held in the hub and pivotal about its longitudinal axis therein, and means for turning the blade in the hub, including a worm coaxial with the hub, a planetary worm wheel meshing with the worm and carried by the hub and means connecting the Worm Wheel and the blade for turning the latter in response tota speed differential between the hub and Worm, including a lever fastened to the blade outside the hub.

15. In a controllable pitch propeller, a hub,

-means for driving the hub, a blade pivotal about its longitudinal axis in the hub, and means for turning the blade in the hub, including a worm concentric with the axis of the hub, a lever attached to the blade outside the hub, planetary means rotatable with the blade and meshing with the worm, and means connecting said lever and last named means.

16. Means for varying the pitch angle of a propeller blade while in rotation, comprising a friction driven Worm gear coaxial and normally revolving with the propeller, braking means anchored on a fixed member and operatively connected with said worm for limiting the rotative speed thereof relatively to the propeller, and means for applying said difference of rotative speed to the turning of said propeller blade on its longitudinal axis, comprising a worm wheel operatively connected to the blade and having its axis arranged transversely of the axis of the blade, said Worm wheel being rotatable with the blade about the periphery of the worm gear.

' CHARLES T. CHANCE.

MURRAY K. PATTEN. 

